Metal oxide plating for maximizing the performance of ruthenium(IV) oxide-catalyzed electrochemical oxygen evolution...

Hydrogen production by proton exchange membrane water electrolysis requires an anode with low overpotential for oxygen evolution reaction (OER) and robustness in acidic solution. While exploring new electrode materials to improve the performance and durability, optimizing the morphology of typical materials using new methods is a big challenge in materials science. RuO₂ is one of the most active and stable electrocatalysts, but further improvement in its performance and cost reduction must be achieved for practical use. Herein, we present a novel technology, named "metal oxide plating", which can provide maximum performances with minimum amount. A uniform single-crystal RuO₂ film with thickness of ∼2.5 nm was synthesized by a solvothermal-post heating method at an amount (x) of only 18 μg cm^-2 (ST-RuO₂(18)//TiO₂ NWA). OER stably proceeds on ST-RuO₂(18)//TiO₂ NWA with ∼100% efficiency to provide a mass-specific activity (MSA) of 341 A g_cat^-1 at 1.50 V (vs. RHE), exceeding the values for most of the state-of-the-art RuO₂ electrodes.